Electric-furnace heating unit



Sept. 29, 1925. 1,555,292.-

A. D. KER-ENE ELECTRIC FURNACE HEATING UNIT v Filed July 20, 1923 2 shebssheet 1 ITNESSES' INVENTOR I ATTORNEY Patented Sept. 29, 1925.

UNITED STATES PATENT OFFICE.

ALVIN D. KEENE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRIC-FURNACE HEATING UNIT.

Application filed. July 20, 1923.

To all whom it may concern:

Be it known that I, ALVIN D. KEENE, a

citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electric-Furnace Heating Units, of which the following isa specification.

My invention relates to electric heating devices and particularly to electric heating units for electric resistance furnaces. V

The object of my invention is to provide a relatively simple and compact structure for a removable and self-contained heating unit of relatively high capacity, that may be operated at relatively high temperatures. In practicing my invention, I provide a resistor wire that is wound in the form of a flat helix, the adjacent turns of which are spaced from each other. Refractory members, of electric-insulating material, having a plurality of spaced pockets on one face thereof operatively engage the end portions of each turn which are located in said pockets.

A metal frame that is provided has side pieces of overhung channel section interfitting with the refractory members to hold them in proper operative positions, and end pieces suitably secured to the side pieces. The ends of the resistor member extend through insulating bushings in the endpieces. In the drawings,

tion, through an electric resistance furnace embodying my invention,

Fig. 2 is a view, in side elevation, of a heating unit embodying my invention,

Fig. 3 is a view, in lateral section, therethrough, taken on the line III-III of Fig. 2,

Fig. 4 1s a view, in side elevation, of a modified form of device embodying my invention, and

Fig. 5 is a view, in lateral sectionthere through, taken on the line VV of Fig. IV.

An electric resistance furnace 11 comprises a plurality of outer side walls 12, a-

a plurality of bricks or blocks of a suitable Figure 1 is a view, in vertical lateral sec- Serial No. 652,674.

high-temperature-resisting refractory material usually employed in the art.

The walls are so spaced apart as to provide a furnace chamber 16 of any suitable or desired contour and dimensions. I have shown a furnace structure for illustrative purposes only in order to show more particularly the heavy resistor member 18 in the form of a wire or rod that is preformed t0 the shape of a flat helix, as is more particularly illustrated in Fig. 8 of the drawing. The adjacent turns of the helix are spaced a suitable distance apart in accordance with the dimensions of the wire and the dimensions of the helix. A plurality of refractory supporting members 19, of a suitable electric-lnsulating and high-temperature-resisting mate rial, are provided and have a plurality of spaced pockets 21 in the inner face thereof into which the rounded end portions of each turn of the resistor member 18 may be fit. The distance between the adjacent turns of the resistor member 18 should be sufliciently large to make the walls between the adjacent pockets 21 sufficiently heavy to resist such strains as may be placed thereon during the assembly and disassembly of the heating unitsand during the operation thereof.

A metal frame is provided for the members 19, a number of which are located in end-'to-end relation at each side portion of the flattened helix and comprises a pairof metal side members 22 0f substantially overhanging channel form in lateral section. The overhanging flanges of the side members co-operate with the refractory members 19 to interfit therewith, a side shoulder portion 23 being provided at each side of the members 19 substantially as illustrated in Fig. 3 of the drawings.

The members 19 are placed in their proper operative positions within the co-operatingv side members22 by armovement longitudinally thereof. End members 24, also of metal, are provided at each end of the side members 22 to which they are bolted, by suitable bolts 25 and co-operating nuts 26.- This construction provides asubstantially rectangular metal frame, preferably, of a to substantially a right angle of the plane.

of the turns of the helix and extendsthrough an insulating thimble 27 that is mounted in an opening 28 in the end mem-' ber 24. A positioning ring 29 may be provided acentto the outer edge of the thimble 2? to locate it in the opening 28. WVhere it is desired to. connect and support the hereinbefore described heating units in series circuit relation, I prefer to employ a connector of the type disclosed and claimed in my copending application, Serial No. 649,- 7 81, filed July 6, 1923, and assigned to the IVestinghouse Electric & Manufacturing Company.

Other forms of terminal construction may, of course, also be employed and are not par? ticularly illustrated or described.

IVhere it is considered desirable to make the individual heating unit of substantial double the. length illustrated in Fig. 2 of the drawings, I employ the construction disclosed in Figs. 4 and 5, of the drawings. The heatingunit there illustrated comprises an integral double flat helix of resistor wire 18, a short intermediate integral part of the member 18 being bent a-t substantially right angles. to the plane of each of the turns of the helix, as indicated more, particularly by the portion 81 in Fig. 4 of the drawing.

A pair of metal side frames 32 that are provided, interfit with, and support, a plumembers 3 1, of angle bar form in lateral section, may be bolted, as illustrated more particularly in Fig. 50f the drawing. Bolts 35 and nuts 36 hold the two members 34 in closely adjacent relation. An opening 37 is formed by the two members 34 intermediate their endsand a thimble 38 is located therein, the thimble'being of refractory electricinsulating material.' End pieces 24 are provided of the same type as'hereinbefore described for the single'heating unit.

In assembling this unit, the refractory members 19 are movedinto theirproper operative position longitudinally of the side members 32" from each end-thereof, after which the twoside-- members, 7 together with the refractory-- blocks-'19. may be placedinproper operative position relatively to a preformed heating unit comprising the two flat helically wound coils. The two portions of the split thimble 38 may be placed around the intermediate portion 31 of the resistor member 18, then the two parts 3% may be placed in their proper operative positions, and bolted together and to the side members. Then the end members 24, together with the thimbles 27 may be placed in their proper operative positions after which the unit is ready for installation.

Any desired means of mounting a plurality'of the units in the furnace structure 11 may be employed, and I have illustrated a plurality of metal rods 39 of nichrome or other suitable high temperature resisting material that are mounted in the refractory walls and extend outwardly therefrom a sufficient distance to permit of mounting therein a key member 41, of substantially l.- shape, that is effective to prevent lateral movement of the heating unit relatively to the wall against which it is located.

At the right-hand side of the furnace structure in Fig. 1, I have illustrated a slightly modified form of'mounting in which a pair of the hereinbefore described heating units may have the side members located in closely adjacent relation bolted together in order to hold the two units in proper operative positions relatively to each other. The lower unit may rest directly on the floor and the top edge of the upper unit may be held against the wall in. any desired manner, as by the use of the rods 39 and the key members 451.

Any desired method of'bringing out the end portions of the heating units through the furnace structure may be employed and I have illustrated an insulating bushing 42 located in the furnace wall, through which the ends of the resistor member 18 may extend. The device embodying my invention provides a double layer of heating element, the two layers of which may be located a relatively smalldistance apart. and'by spacing the adjacent turns a suitable distance from each other, substantially all of the re sistor wire is in direct heat-radiating rela tion to a furnace chamber in which it is located. This makes it possible to obtain a relatively high value of watts per square inch radiated asheat from each unit of area of the furnace wall, while at the same time, the watts per square inch of radiating surface of the resistor member itself is maintained at a relatively low value. This results in a heating element that has a long life, while making it permissible to obtain relatively high temperature in the furnace chamber in which such heating unit is employed.

Anymovement of the end portions :of each turn of thev resistor member proper is: pre

vented in both a lateral and a longitudinal direction relatively to the heating unit and the metal frame of the heating unit protects the resistor member proper against accidental contact with material being placed in, or being removed from, the furnace chamber.

Various modifications and changes may be made without departing from the spirit and scope of the invention, I desire, therefore, that only such modifications shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.

I claim as my invention:

1. An electric heating unit comprising a helically wound resistor wire, refractory supporting members having spaced pockets therein for receiving a relatively small portion only of each turn of said resistor wire, and means for holding said refractory supporting members in operative engagement with said wire.

2. An electric heating unit comprising a fiat helix of resistor wire, refractory members of electric-insulating material having spaced pockets therein for receiving the end portions only of said turns of resistor wire, and metal members interfitting with said refractory members for holding them in operative engagement with resistor wire.

3. An electric heating unit comprising a metal frame having side members of substantially overhung channel form in lateral section, refractory members of electric-insulating material located in and supported by said side members and having a plurality of spaced pockets in one face thereof, and a resistor member comprising a wire or rod bent to form a flattened helix, the narrow end portions of which are located in said pockets.

4. An electric heating unit comprising a resistor member wound in the form of a flat helix with the adjacent turns spaced from each other, and refractory supporting members, of electric-insulating material, operatively engaging the outer surface of the end portions only of the turns of the resistor member and having integral means com rising pockets therein for preventing 0th lateral and longitudinal movement of the respective turns thereof.

5. An electric heating unit comprising a resistor member wound in the form of a flat helix with the adjacent turns spaced from each other, refractory supporting members, of electric-insulating material, operatively engaging the outer surface of the end portions only of the turns of the resistor member and having integral means comprising pockets therein for preventing both lateral and longitudinal movement of the respective turns thereof, and metal members interfitting with said refractory supporting members for holding them in proper operative positions relatively to the resist-or member.

6. In an electric heating unit, in combination, a metal frame having side pieces of overhung channel section and end pieces secured to said side pieces, refractory members of electric-insulating material interfitti'ng with and supported by said side pieces and having a plurality of spaced pockets in the opposing faces thereof, a resistor member preformed to comprise a flattened helix having the end portions of each turn located in said spaced pockets, and having the ends of the resistor member extending through and insulatedly supported by the metal end pieces of said frame.

In testimony whereof, I have hereunto subscribed my name this 2nd day of July 1923.

ALVIN D. KEENE. 

